As a conventional ultrasonic probe, for example, as described in the following patent documents 1, 2 and 3, a method of transmitting a rotation of a motor through a wire to an ultrasonic transducer is known. FIG. 8 shows a sectional view of the conventional ultrasonic probe. Inside a grip portion 1, a motor 5 and a pulley 102 linked to its rotation shaft are placed. Inside a tip portion 3 of an insertion portion 2, an ultrasonic transducer 4 and a pulley 7 linked to its rotation shaft 9 are placed. Then, an endless wire 8 is laid between the pulleys 102, 7, and the rotation of the motor 5 is transmitted to the rotation shaft 9 of the ultrasonic transducer 4.
Patent Document 1: Japanese Patent Application publication (H10-179588) (FIG. 3, Paragraph 0049)
Patent Document 2: Japanese Patent Application publication (H10-174686) (FIG. 1, Paragraph 0052)
Patent Document 3: Japanese Patent Application publication (2001-170053) (FIG. 2, Paragraph 0010)
However, in the foregoing conventional ultrasonic probe, the wire 8 is laid so as to be extended from the grip portion 1 to the tip portion 3 of the insertion portion 2, and it is relatively long. Thus, this has a problem that looseness of the wire 8 is generated, which causes a positional error of the ultrasonic transducer 4.